pub trait Hasher: Default + Send + Sync {
type Size: Size;
type Digest: Digest<Self::Size>;
fn digest(input: &[u8]) -> Self::Digest;
fn size() -> u8 { ... }
}Expand description
Trait implemented by a hash function implementation.
It specifies its own Digest type, so that the output of the hash function can later be
distinguished. This way you can create a MultihashDigest from a Digest.
Every hashing algorithm that is used with Multihash needs to implement those. This trait is
very similar to the external digest::Digest trait. There is a small significant
difference, which needed the introduction of this Hasher trait instead of re-using the
widely used digest::Digest trait.
The external digest::Digest trait has a single return type called Output, which is used
for all hashers that implement it. It’s basically a wrapper around the hashed result bytes.
For Multihashes we need to distinguish those bytes, as we care about which hash function they
were created with (which is the whole point of Multihashes). Therefore the Hasher trait
defines an associated type Hasher::Digest for the output of the hasher. This way the
implementers can specify their own, hasher specific type (which implements Digest) for
their output.